The present invention pertains to a process for providing a consistent, continuous and/or repeating signal. More particularly, the present invention pertains to a method and apparatus for creating a continuous/repeating signal/data stream from an original source signal/data stream, and providing this signal/data stream continuously/repeatedly.
It is known in a variety of arts to use devices known as processors to modify signals from a variety and multiplicity of sources. The processors themselves have varying numbers of controllable parameters, with varying degrees of complexity in the setting of each parameter. Generally, a human operator, or constructed control device, makes these adjustments on the basis of some perception of the results of adjustments as they are made. A common occurrence in the audio field supplies a simple example. In a situation where it is desired to amplify or record a musical instrument, an electronic signal (or digital or other useful signal) is usually presented via a microphone (or other sound transducer) and its associated amplifier. Typically, this signal is then modified through one or several processors such as equalizers, filters, compressors, reverberators, and many other effects devices. A musician will play the musical instrument repeatedly, so a sound engineer can listen to changes in the sound produced by the processor(s) as he varies each control parameter of each processor. Under these circumstances, three problems arise while modifying the signal:
1 The listener must hear ONLY the electronic sound being modified, so the original acoustic sound must be isolated from the listener. This is normally accomplished in a recording studio by having separate, acoustically isolated rooms for playing and listening or by recording the instrument (onto tape, etc.) and then using the recording as the sound source.
Some headphones provide a limited degree of isolation, and are used when isolation from the acoustic sound is impossible (usually in live performance situations) or unaffordable.
2 The performer must play a variety of short phrases over and over, so that the listener can hear the effects of the equipment being used. (With musical material varying, it is difficult to judge whether a change is due to a knob turned or a note played more loudly or differently). This process can be very draining on a performer, as making adjustments carefully enough to get a good sound for either recording or live playing can take a lot of time. Also, many performers are not good at playing a phrase consistently, which makes the listener/engineer""s job difficult or impossible.
3 If the performer and listener are the same, and a recording system is not available, the only recourse available (beyond just guessing) is to use headphones, with the limited isolation mentioned above. For loud instruments (e.g., drums), there is no headphone that provides enough isolation to do a good job. For a singer, headphones do not isolate at all, because there is an internal sound transmission through the singer""s body.
These problems are not pertinent in situations where the signal does not require acoustic isolation, but other problems may arise. For example, a signal source may have a degree of randomness that makes the adjustment of a processor parameter difficult, although the processor will be able to accomplish its goal once properly set.
These and other problems are addressed by a method and apparatus of the present invention. According to an embodiment of the present invention, a system can be customized to take a conveniently small test signal (such as a short musical phrase for the example above), record it on a suitable medium, and play it repeatedly into any desired processor or other system. In one embodiment of the present invention, standard components can be used to build a device where:
1. A short length, limited use sampler (or other recording medium) of adequate quality is set into READY MODE,
2. Upon an operator""s signal, or upon detecting the desired signal at a pre-selected level (a xe2x80x9cthresholdxe2x80x9d), an appropriate length (e.g., about 1 or 2 seconds) of sound or other signal is recorded, and
3. The recorded signal can be immediately played continuously (i.e. xe2x80x9cloopedxe2x80x9d), allowing the operator to make the necessary adjustments to the processor(s).
Specifically, for the acoustic example above, some of the advantages of the system are:
1. There is no need to record a long section of signal, and no other recording equipment is needed.
2. There is no need for an isolated room.
3. Where the signal is generated by a musician or other person, the performer does not have to play test phrases repetitively, avoiding mental and physical fatigue. Under many circumstances, even a non-musician can generate a phrase well enough so that the performer is not needed for processor adjustments at all. Also, the xe2x80x98perfectxe2x80x99 consistency of a repeated loop is often the ideal signal for adjustments of this type, and is therefor often a better test signal than even a good player may provide.
4. Where the signal is generated by a musician or other person, a recorded version of the signal may be the only possible way to allow that same person to be the operator making adjustments (that is, for the performer to be directly involved in the sound control process). This is particularly true for a singer, who can never be isolated from his/her voice. A recorded signal is the only known solution. In live performance situations, recording may not be feasible or available. The present invention allows a singer to control the process of creating the xe2x80x9csoundxe2x80x9d that his/her voice will make through the sound system that the audience will be listening to.
5. For any specific circumstance or set of circumstances, experimentation can be used to optimize the length and speed of repetitions to allow quickest adjustment and minimum fatigue in listening.
According to the present invention, this process can be accomplished using a commercially available sampler. This is cumbersome, as it requires patching or switching the sampler into some pre-processor point in the signal path, and requires several steps in the sampler""s operation, such as RECORD, TRIM SAMPLE, and SET LOOP LENGTH.
In some circumstances, two (or more) signals may have interactions that require adjustments to be made interactively. One such circumstance is when dealing with acoustic signals, where there is often more than one sound source in use at a time. For example, there may be two instruments playing in close proximaty, such as a violin and a piano. Also, some musical instruments often require the use of more than one microphone (common examples are a piano and a drum set). Each microphone is placed to pick up only a particular instrument or part of an instrument. In practice, the sound from other instruments or unwanted regions of the same instrument xe2x80x9ccrossesxe2x80x9d into all microphones. This is called acoustic crosstalk. The sound of an instrument""s crosstalk into other microphones sometimes approaches or even surpasses the level of that instrument""s sound in its own microphone. Thus, when modifying a single microphone""s signal, it is important to be able to hear the microphone""s signal mixed with any other pertinent microphone signal, as well as alone, so that the final product is as desired. A two channel version of the system, one channel for each signal, accomplishes this.
The problems as described for two source signals are the same for more than two source signals. The solution is to have one channel for each signal. For circumstances where this is not practical, a method is provided to accommodate multiple signal channels with the use of only two sampler channels; channel A for the signal being modified, and channel B for a mix of all other pertinent signals as they will be perceived in relation to channel A. For the acoustic example described above, by turning channel B off and on, the listener can switch back and forth between the single microphone alone (where it is easiest to hear how the sound is being affected) and in combination with all the other microphones, (which will be the final product required). This embodiment is presented below, along with a switching mechanism to facilitate use with a multiplicity of signals that need to be adjusted.